Slitherine

I'm playing with krabi1966 the Return To Kiev map. In the second day when I'm looking at the opponent turn the game is freezing. It seems that there are some invisible units on the map (or at least I don't see them, maybe the picture is not present in my game version). My units were attacked from an empty position and then the game froze.
DirectX 11, Windows 7

1966 ???

If that is correct, it is a custom map with custom units.

You will need the appropriate files to play that map.

Or "krabi1966" is a user name

Yes, as he mentioned he played "Return to Kiev".

One possible cause could be if this scenario might have been revised in a recent patch to use a unit not present in version 1.0 of the game, but their matchup is using an older equpment file. At least "invisible crashing unit" sounds like a scenario file referencing a unit number not defined in the pzeqp...?

For instance, the current version of the Gazala Line AK scenario has been updated to feature SAS units (as opposed to regular British paratroopers named "SAS"). This scenario would probably crash in exactly this way if played using an unpatched equipment file.